This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 37 |
| 6 | 122 |
| 7 | 346 |
| 8 | 913 |
| 9 | 2398 |
| 10 | 6515 |
| 11 | 18317 |
| 12 | 52226 |
| 13 | 148408 |
| 14 | 417810 |
| 15 | 1168085 |
| 16 | 3258813 |
| 17 | 9103828 |
| 18 | 25488736 |
| 19 | 71462437 |
| 20 | 200406479 |
| 21 | 561770980 |
| 22 | 1573939555 |
| 23 | 4408629727 |
| 24 | 12348599802 |
| 25 | 34592601763 |
| 26 | 96916209910 |
| 27 | 271537125048 |
| 28 | 760777555986 |
| 29 | 2131439888257 |